This invention relates to the field of game balls. More specifically, this invention relates to a multi-layered game ball product and a process for the manufacture thereof.
Efficient manufacturing processes for game ball products having a single layer are well known. The game ball product can be a finished game ball or form the core of a finished game ball. Game ball products produced of a single layer of a material can display less than optimal characteristics. The material of the single layer typically must be capable of performing several different functions simultaneously. For example, a single layer basketball must be constructed of a material that can form an air-tight bladder. In addition, the same material must provide abrasion resistance for an adequate product life for the game ball product. Furthermore, the same material must have dimensional stability for the game ball product to resist overexpansion as the ball is inflated and is used during the product lifetime. Single layer materials typically cannot provide optimal characteristics for all the performance requirements.
Given these differing operational requirements and deficiencies of a single layer game ball product, it is well known to produce a game ball product having multiple layers of differing materials. Each layer of the multi-layer game ball product is directed to providing a specific function or characteristic for a given performance requirement. For example, a game ball product may be produced of two layers. The outer layer provides abrasion resistance, and the inner layer, such as a bladder, provides an air-tight seal for the game ball product. Multi-layer game ball products therefore typically have superior performance characteristics relative to single layer game ball products. However, multi-layered game ball products typically require additional manufacturing steps compared to the production of the single layered game ball product. Therefore, multiple layered game ball products typically have a higher relative production cost and a more extended production time.
For example, basketballs are conventionally constructed by cold molding or hand laying panels of rubber, leather or synthetic leather onto a basketball carcass. These multi-layer basketballs typically require additional manufacturing steps in comparison to a single layer game ball product.
Single and multi-layer game ball products are also used as game ball cores. Game ball products employed as game ball cores for baseballs and softballs are known to be manufactured of flexible, semi-rigid and rigid polyurethane foam, rotational molded polyolefins, foamed ionomers, cork, kapok and wound string. These conventional game ball cores typically require multiple manufacturing steps in addition to further manufacturing to apply an outer shell to the core. Each additional manufacturing step typically increases final cost of the finished game ball.
Briefly stated, the invention is for the process of manufacturing a multi-layered game ball product wherein at least the inner layer is formed by a molding process. More specifically, the invention is for the process of manufacturing a multi-layered game ball product by forming the game ball product within a mold wherein at least the inner layer of the game ball product is formed by the blow molding of a parison.
The process of the invention is for forming a game ball product having an inner and an outer layer. A parison is formed of at least the inner layer. The outer layer is formed. The inner and outer layers are introduced into a mold. The parison is then expanded to form a multi-layer game ball product.
The process of the invention allows for production of multi-layer game ball products by a reduced number of manufacturing steps relative to the number of manufacturing steps required for conventional processes to manufacture multi-layered game ball products. The process of the invention employs blow molding to manufacture a multi-layered game ball product. The inner layer of the game ball is preferably extruded in a partial melt state to form a parison. The parison can also have 1-5 additional co-extruded layers, each layer preferably chosen to optimize a particular performance requirement of the final game ball product. Pressurized gas is then introduced into the parison to expand the parison against the mold to form the game ball product. After the game ball product has sufficiently cooled, the game ball product is removed from the mold.
In one preferred embodiment of the process, a co-extruded three layer parison is blow molded to form a finished game ball. The material of the outer layer is selected for feel and abrasion resistance. The material of the intermediate layer is selected for dimensional stability when the game ball product is inflated and the material of the inner layer is selected for air entrapment. The parison of the three layers is blow molded to form the finished game ball product.
In a further embodiment of the invention, particularly suited for the manufacture of basketballs, an inner layer can be blow molded onto pre-cut panels supported on the inside surface of a mold to produce a multi-layered game ball product. For example, a multi-layered basketball can be produced by vacuum supporting outer layer panels of synthetic leather on the inside of a basketball mold. The inner layer of the basketball is extruded in a partial melt state as a parison into the mold and blow molded onto the outer layer panels. The parison in the partial melt state bonds to the synthetic leather panels to form the finished multi-layer basketball. As an alternative, an adhesive can be applied to the outer layer panels prior to the blow molding to provide bonding between the inner layer and the outer layer panels.
In still another embodiment of the invention, the multi-layered game ball product can be injected with a filler subsequent to blow molding of the parison. For example, a softball can be produced by blow molding a multi-layer parison onto a softball mold to form a game ball shell. The resulting game ball shell is then filled with a foam to complete the finished game ball.
In addition, the filled game ball product manufactured by the process of the invention can be employed as the core for a finished game ball. An additional outer layer can be molded onto the filled game ball product. Alternately, a conventional softball or baseball cover can also be stitched onto the filled game ball product to form the finished game ball.
An object of the invention is to provide a production process for the efficient manufacture of a multi-layered game ball product.
Another object of the invention is to provide a production process to manufacture a multi-layered game ball product with a reduced number of production steps relative to a conventional multi-layer game ball product process of manufacture.
A further object of the invention is to provide a production process having an increased production rate of game ball products.
A still further object of the invention is to provide a game ball production process having reduced costs relative to conventional production processes of multi-layer game ball products.
These and other objects of the invention will be apparent from the following description and figures.